Search

A 3D heterometallic oxalate-bridged coordination polymer [CuIIFeII2(H2O)(terpy)(C2O4)3]n (terpy = 2, 2′:6′, 2″-terpyridine) (1) was investigated both as photocatalyst for the organic dye removal and as a single-source precursor for the preparation of the copper ferrite (CuFe2O4) nanocrystals by thermal processing. The dual functionality of 1 was supported by the degradation of aqueous solutions of rhodamine B (RhB) and methylene blue (MB) solutions under visible (Vis) and ultraviolet (UV) light irradiation, powder X-ray diffraction data collection at room temperature, and the optical and scanning electron microscopy analyses. A close inspection of the X-ray diffraction patterns unveiled qualitative and quantitative information on the phase composition obtained after the single-source molecular precursor route to spinel oxide. By optimizing the temperature levels and setting the controlled heating rate at 6 h of holding time, the phase composition of thermal processing of 1 was evaluated—thermal treatment of 1 at 950◦C for 6 h and a heating/cooling rate of 10◦C min−1 resulted in the formation of solely tetragonal spinel phase of CuFe2O4, whereas the formation of both tetragonal and cubic CuFe2O4 phases was observed at 950◦C by the heating rate of 30◦C min−1. To obtain the high-temperature cubic CuFe2O4 oxide, compound 1 was heated and then quenched at 925◦C, which led to the formation of the cubic spinel ferrite as the main crystalline oxide phase. Moreover, the photocatalytic properties of the t-CuFe2O4 spinel were investigated under the same conditions as for 1. The optical bandgap energies were estimated from UV–Vis absorption spectra for both metal oxide and precursor powder.

Rad se sastoji od urbanističkog i projektantskog rješenjazapodručje poslovne zone Gacka. Urbanističko rješenje nastajeiz brojnih provedenih analiza šireg i užeg gradskog kontekstate je utjelovljeno spojem dvaju tipologija - lamele (bloka/petlje) i tornja. Iz postavljenog koncepta urbanizma slijedi arhitektonsko oblikovanje jednog od pet predviđenih tornjevate njemu pripadajućeg dijela lamele. Glavna misao vodiljabilaje razdvanjanje zadanog programa, a samimtime i zgrade, nadva dijela - kreativni i logički, poput dvije suprotnosti koječineljudski mozak. Ideja se provodi tlocrtno, kroz presjek tekrozsamu materijalnost odjela - kontrast toplo-hladno, mramor- drvo. Pročelja su oblikovana minimalistički i anonimno koristeći sitovi beton i reciklirano platno. Nakonsviharhitektonskih nacrta slijede sheme konstrukcije i instalacija., The paper consists of urban and architectural solution for thearea of Gacka business zone. The urban solution arises fromnumerous analyzes of the wider and narrower urban context and is embodied by the combination of two typologies - lamela(block / loop) and tower. The architectural design consistsof designing one of the five planned towers and a part of theloopthat goes with it. The main guiding thought was to separatethe given program, and thus the building, into two parts - creative and logical, like the two opposites that make upthehuman brain. The idea is implemented in the floor plan, through the cross-section and through the very materialityof the department - warm-cold and marble-wood contrast. Thefacades are designed minimalistically and anonymously usingconcrete sieves and recycled canvas. All architectural designsare followed by construction and installation schemes.

Pojam zdravlja ima brojne definicije koje na različite načine opisuju težnju za stanjem koje je neophodno svakom čovjeku, a okosnicu svih različitih objašnjenja tvori činjenica da je ono jedno od temeljnih ljudskih prava i vrednota. Termin zatvorenik označava osobu kojoj je izrečena kazna zatvora zbog kaznenog djela i koja se nalazi na izdržavanju kazne zatvora u kaznionici, odnosno zatvoru. Zbog same prirode načina izvršavanja kazne zatvora, izdvajanja počinitelja iz njegove sredine, oni su jedna od najranjivijih skupina društva kada govorimo o povredama njihovih prava i mogućnostima njihove zaštite. Temeljno načelo pružanja zdravstvene zaštite zatvorenicima, polazi od toga da oni trebaju uživati iste standarde zaštite kao i ostatak zajednice i da im treba biti omogućen pristup svim zdravstvenim uslugama koje su dostupne u državi, bez diskriminacije. Poseban osvrt u radu odnosi se na zatvorenike s duševnim smetnjama jer, iako koračamo 21. stoljećem, zajednica još uvijek nije dovoljno upućena u problematiku osoba s duševnim smetnjama i njihovim potrebama., The term health has numerous definitions that in different ways describe the aspiration for the state that is necessary for every human being. The basis of all different explanations is the fact that health is one of the fundamental human rights and values. The term prisoner signifies a person who has been sentenced to imprisonment for a criminal offense and who is serving a prison sentence in penitentiaries or prisons. Due to the nature of the execution of the prison sentence, that is the separation of perpetrators from their surroundings, they are one of the most vulnerable groups in society when it comes to violations of their rights and possibilities to protect them. The fundamental principle of providing health care to prisoners is that they should enjoy the same standards of care as the rest of the community and that they should be given access to all health services available in the country, without discrimination. A special review of the paper refers to prisoners with mental disorders because, although we are entering the 21st century, the community is still not sufficiently aware of the problems of people with mental disorders and their needs.

Recently, proton conductivity of the metal-organic frameworks (MOFs) has been considered as a new functionality, mainly due to their crystallinity, high porosity, designability and tunability in structure and properties, and potential application in solid-state electrolytes. The simplest method to introduce proton carriers is to include a counterion such as hydronium (H3O+), ammonium [NH4+, (CH3)2NH2+, ...] or an anion (SO42−), resulting in charged compounds. The counterions form the hydrogen-bonding arrays with the guest water or other constituents of compound, creating proton-conducting pathways.1, 2 A very important role in the design and synthesis of multifunctional materials belongs to the oxalate moiety, C2O42−, due to its various possibilities of coordination to metal centers and its ability to mediate electronic effects between paramagnetic metal ions. The proton conductive materials must have good water and chemical durability under the influence of humidity and temperature, and in general, oxalate-based systems have regular structures and stable frameworks. In addition, the oxygen atoms of the oxalate group can construct complex hydrogen-bonded networks, which are more than suitable for proton conduction. Although high proton conductivity is often found in two-dimensional (2D) and three-dimensional (3D) oxalate-based compounds, the low-dimensional structures can have excellent proton conductivity properties via the hydrogen-bonding chain because a low void space can be advantageous for proton hopping.2, 3 We explored the proton conduction behaviour of three oxalate-based compounds of different nuclearity and dimensionality, prepared and characterized in our group: homometallic discrete mononuclear (NH4)2[Fe(H2O)Cl3(C2O4)]·H2O (1) and one-dimensional (1D) {; ; [NH(CH3)(C2H5)2][FeCl2(C2O4)]·H2O}; ; n (2), and 2D heterometallic {; ; [NH(CH3)2 (C2H5)]8[Mn4Cl4Cr4(C2O4)12]}; ; n (3). The proton conductivity of 1, 2 and 3 at 298 K increases with increasing relative humidity (RH), achieving values of 2.17 × 10−3 (Ω cm)−1 at 74% RH, 2.70 × 10−4 (Ω cm)−1 at 93% RH and 1.6 × 10–3 (Ω cm)–1 at 90% RH, respectively. From the obtained values, it can be confirmed and concluded that the amount of protonated proton carriers acting as proton donors, the number of non-protonated sites acting as proton acceptors, and the efficient proton transport pathway made of H-bonding network are extremely important for obtaining materials with high conductivity, rather than their dimensional arrangement. References (1) X.-X. Xie, Y.-C. Yang, B.-H. Dou, Z.-F. Li, G. Li, Coord. Chem. Rev. 2020, 404, 213100. (2) D-W. ; Lim, H. Kitagaw, Chem. Soc. Rev. 2021, 50, 6349-6368. (3) S. Burazer, K. Molčano, A. Šantić, T. Klase, E. Wenger, D. Pajić, Z. Jagličić, J. Popović, M. Jurić, Materials 2021, 14, 5543. Acknowledgement This work has been funded by the Croatian Science Foundation under project number IP-2019-04-5742.

Multifunctional properties of the metal-organic coordination compounds can be achieved by combining the intrinsic properties of the host, especially the magnetic ones, with an additional functionalities originating from the selected guest molecules. The oxalate group, C2O42–, has proven to be one of the most versatile ligands used in the preparation of these systems. Due to its different coordination modes towards the metal centres, as well as its ability to mediate magnetic interactions between paramagnetic metal ions, a large number of oxalate-based transition metal species of different dimensionality have been synthesized and characterized, many of them having tunable magnetic frameworks. Most of the oxalate-bridged systems described to date have been obtained by the "complex-as-ligand" approach ; a building block, the tris(oxalato)metalate [MIII(C2O4)3]3− anion, is used as a ligand toward other metal ions. The topology of these compounds is controlled by a templating counterion.1 Proton conductivity has recently been considered as a new functionality of metal-organic compounds ; the simplest method to introduce proton carriers is to incorporate a counterion such as hydronium (H3O+), ammonium [NH4+, (CH3)2NH2+, ...] or an anion (SO42−), resulting in the charged compounds. The counterions form the hydrogen bonds with the guest water or other components of compound, forming proton-conducting pathways consisting of hydrogen bonding networks. The oxygen atoms of the oxalate group may also be involved in the formation of hydrogen bonds, which makes oxalate systems suitable for electrical property research in addition to their their high crystallinity and high stability to water.2, 3 Further, the use of heterometallic complexes or frameworks as single-source precursors provides simplified synthetic routes through one-step thermal decomposition to form mixed metal oxide materials. The advantage of a solid phase transition is the retention of the elemental composition defined by the molecular precursor with only a loss of volatile decomposition products – allowing excellent stoichiometric control of the intermetallic ratio in the oxide products.4 To achieve our ultimate goal – the exploration of complexes with remarkable structural, magnetic and electrical properties1, 2 three novel heterometallic oxalate-bridged compounds were obtained from the reaction A3[CrIII(C2O4)3] [A = (C2H5)2(CH3)NH+ or (C2H5)(CH3)2NH+], as ligand towards manganise(II) ions and N-ligand [2, 2'- bipyridine (bpy) or 2, 2' ; 6', 2''-terpyridine (terpy)]: trinuclear [NH(CH3)(C2H5)2][{;Mn(bpy) (H2O)Cl};2Cr(C2O4)3] (1a) and [NH(CH3)2(C2H5)] [{;Mn(bpy)(H2O)Cl};2Cr(C2O4)3] (1b), and dinuclear [terpyH][Mn(H2O)2(terpy)Cr(C2O4)3]·4H2O (2). Unlike compounds 1a and 1b, which were obtained with a smaller bidentate 2, 2'-bypiridine ligand, the use of a bulky tridentate N-donor ligand terpyridine does not allow the incorporation of an alkyl ammonium cation into the structure of 2. This compound was tested as a single molecular precursor for the preparation of MnCrO4 oxide in one step, due to its suitable metal ratio. The oxalate group, C2O42−, easily decomposes at low temperatures into gaseous CO2 and CO, and thus the oxalate‐based solids can serve as suitable precursors for preparation of mixed metal oxides.1, 4 In addition to the powder and single crystal X-ray diffraction, obtained compounds were characterized by thermal analysis, IR and impedance spectroscopy.

Heteropolynuclear metal complexes have been extensively studied for their ability to form various architectures and topologies, from discrete polynuclear metal compounds to polymeric one- (1D), two- (2D) or threedimensional (3D) assemblies, featuring a range of distinct magnetic properties. In recent decades, the chemistry of oxalate-containing complexes has become an active area of research – the oxalate moiety, C2O42−, acts as a linker between metal centres with various possibilities of bridiging modes and has the ability to mediate magnetic interactions between paramagnetic metal centres. Stable mononuclear anionic oxalate complexes such as tris(oxalato)metalate anions, [MIII(C2O4)3]3− (MIII = Mn, Cr, Fe, V), are often used as ligands toward another metal ion for the preparation of extended multifunctional systems. Also, the introduction of organic ligands containing N- donors into the metal–oxalate systems also influences the nuclearity of the metal centres and additionally stabilizes their solid-state structures. Applying the layering technique, crystals of the tetranuclear chloride-bridged compounds [Cu4(terpy)4Cl5][M(C2O4)3]·nH2O M = Cr3+ ; n = 9 (1) and M = Fe3+ n = 10 (2)] grew from the reaction of an aqueous solution of K3[Cr(C2O4)3]·3H2O or K3[Fe(C2O4)3]·3H2O, respectively, methanol solution containing CuCl2·2H2O and a tridentate ligand 2, 2′:6′, 2′′- terpyridine (terpy). When Cu(NO3)2·3H2O was used instead of the chloride salt, unexpected change in type of the bridge, oxalate versus chloride, was achieved and crystals of the 1D oxalate-bridged coordination polymers {; ; [Cu4Cr2III(H2O)2(terpy)4(C2O4)7]·10H2O}; ; n (3) and {; ; [CuII2FeIII(H2O)(terpy)2(C2O4)7/2]·6H2O}; ; n (4) together with compound [CuII2(H2O)2(terpy)2(C2O4)] [CuIIFeIII(CH3OH)(terpy)(C2O4)3]2 (5), respectively, have been formed. Further, two polymorphs of 3D coordination polymer [CuIIFeII2(H2O)(terpy)(C2O4)3]n (6a and 6b), crystallizing in the triclinic (a) and monoclinic (b) space groups, were formed hydrothermally, depending on whether CuCl2·2H2O or Cu(NO3)2·3H2O was added to the water, besides K3[Fe(C2O4)3]·3H2O and terpy, respectively. Compounds 1 and 2 exhibit a ground-state spin of 1, which is due to antiferromagnetic and ferromagnetic interactions of Cu2+ ions across the chloride bridges in the tetramers ; ferromagnetic coupling transferred through the oxalate bridge was found between Cu2+ ions in 3, as well as strong antiferromagnetic coupling of the Cu2+ ions mediated by the oxalate ligand in cation moiety, and weak ones between Cu2+ and Fe3+ ions through oxalate bridge in the anion of compound 5. Polymer 6 exhibits an antiferromagnetic phase transition at 25 K

In recent years, great efforts have been made to develop new metal-organic frameworks (MOFs) and coordination polymers (CPs) with photocatalytic potential, especially with respect to the development of photocatalysts for organic pollutant degradation, CO2 reduction, and water splitting for H2 production. Compared to conventional metal oxide semiconductors, well- defined and tailored structures of MOFs offer great advantages for understanding the structure- activity relationship. Their high porosity enables the exposure of active sites for catalysis and facilitates the transport of substrates by creating short migration paths for charge carriers prior to their reaction with substrates, thus improving electron-hole separation.[1] The use of heterometallic complexes or frameworks containing more than one metal as single source precursors provides simplified synthetic routes through one- step thermal decomposition to form mixed metal oxide materials. The advantage of a solid phase transition is the retention of the elemental composition defined by the molecular precursor with only a loss of volatile decomposition products – allowing excellent stoichiometric control of the intermetallic ratio in the oxide products. It is known that the release of organic gases affects the particle size and porosity of the produced oxide ; a higher content of organics in the starting materials allows larger porosity and smaller particle sizes in the decomposition products. In addition, control of the heating rate is important to control decomposition and avoid melting/vaporisation of molecular species that can occur with rapid heating. High temperatures also determine the crystallinity, particle size and porosity of the produced materials, limiting the ability to develop specific properties for applications. By using lower synthesis temperatures, oxides with small particle sizes and large surface areas can be produced.[2] Since it is known that Fe–O clusters can be directly excited by visible light[3], leading to more efficient use of solar energy, and that compounds with iron are much cheaper due to the abundant Fe element on Earth, an oxalate-bridged heterometallic coordination polymer [CuII(H2O) (terpy)FeII2(C2O4)3]n (terpy = 2, 2′:6′, 2′′- terpyridine) with a three-dimensional (3D) network[4], was tested as a photocatalyst for the photodegradation of Rhodamine B (RhB) and methylene blue (MB). The optical band gap and photocatalytic activities were studied in detail. This 3D network [CuIIFeII2(H2O)(terpy)(C2O4)3]n was also tested as a single molecular precursor for the preparation of spinel oxide CuFe2O4 due to the suitable metal ratio. The oxalate group, C2O42-, easily decomposes at low temperatures into gaseous CO2 and CO, and therefore the oxalate‐ based solids can serve as suitable precursors for oxides. The (micro)structural, optical and photocatalytic properties of the (nano)crystalline spinel CuFe2O4 samples, prepared for the first time by a simple molecular precursor‐to‐material route, were presented.

It is well known that the oxalate group, C2O42–, used in the preparation of metal-organic coordination compounds, is one of the most versatile ligands with different coordination modes towards metal centres which likewise has ability to mediate magnetic interactions between paramagnetic metal ions. One of the synthetic strategy for preparation of (hetero)polynuclear species is "building block chemistry" in which a molecular anionic ligand, very often the tris(oxalato)metalate anion, [MIII(C2O4)3]3−, is used as a ligand towards other metal cations. The topology of these compounds is controlled by a templating counterion. Combining the intrinsic properties of the host, especially the magnetic ones, with additional functionalities originating from the selected guest molecules, very interesting multifunctional properties can be obtained. Proton conductivity as a new functionality of metal-organic compounds can be achieved by incorporating a counterion such as hydronium (H3O+), ammonium [NH4+, (CH3)2NH2+, ...] or an anion (SO42−) into the anionic network. The counterions form the hydrogen bonds with the guest water or other components of compound and create proton-conducting pathways consisting of hydrogen bonding networks [1]. In addition, heterometallic complexes as single-source precursors provide simplified synthetic routes through one-step thermal decomposition to form mixed metal oxide materials. The advantage of a solid phase transition is the retention of the elemental composition defined by the molecular precursor with only a loss of volatile decomposition products, which allows excellent stoichiometric control of the intermetallic ratio in the oxide products [2]. Motivated by our previous results [1], we investigated the proton conduction behaviour of the novel oxalate-bridged coordination polymer {;[NH(CH3)2(C2H5)]8[Mn4Cl4Cr4(C2O4)12]};n (1) obtained using an aqueous solution of [NH(CH3)2(C2H5)]3[Cr(C2O4)3] as a building block in reaction with Mn2+ ions. Compound 1, consisting of 2D anionic [Mn4Cl4Cr4(C2O4)12)]n8n– networks and hydrogen-bonded [NH(CH3)2(C2H5)]+ cations between these networks, exhibits remarkable humidity-sensing properties and very high proton conductivity at room temperature [1.60 × 10-3 (·cm)-1 at 298 K under 90% relative humidity]. Moreover, this heterometallic compound was tested as a single molecular precursor for the preparation of MnCrO4 oxide in one step, due to its suitable metal ratio. The oxalate group, C2O42−, easily decomposes at low temperatures into gaseous CO2 and CO, and thus the oxalate‐based solids can serve as suitable precursors for the preparation of mixed metal oxides. In addition to powder and single crystal X-ray diffraction, the obtained compound has been characterized by thermal analysis, IR and impedance spectroscopy.

Design of new materials with targeted physical properties is a very atractive field of research nowadays. In recent years, the structural diversity of metal-organic coordination systems has paved the way for the development of multifunctional materials that combine two or more different properties, especially magnetic and electrical ones. A very important role in the design and synthesis of such materials belongs to the oxalate moiety, C2O42-, due to its various possibilities of coordination to metal centres and its ability to mediate electronic effects between paramagnetic metal ions. The synthetic strategy for the preparation of (hetero)polynucelar species is "building block chemistry", in which a molecular anionic ligand, very often the tris(oxalato)metalate anion [MIII(C2O4)3]3− (MIII = Cr, Fe, Ru, Rh, Mn or V), is used as a ligand towards other metal cations. Starting from the same reactants, the structural uncertainty of the obtained coordination compounds can lead to two basic cases: (i) both the structures and the chemical compositions are different ; the obtained compounds differ significantly from each other, reflecting the great versatility of a self- assembly system ; (ii) the structures are different, but the whole coordination networks have the same chemical composition, when the obtained compounds are classified as supramolecular isomers.[1] Inspired by the structural versatility of oxalate-based [CuFe] compounds containing 2, 2':6', 2"-terpyridine (terpy)[2], seven novel oxalate-based [CuIICrIII] compounds: [Cu4(terpy)4Cl5][Cr(C2O4)3]·9H2O (1 ; terpy = 2, 2′:6′, 2′′-terpyridine), {; ; [Cr2Cu4(H2O)2(terpy)4(C2O4)7]·10H2O}; ; n (2), [Cr2Cu4(H2O)2(terpy)4(C2O4)7]·12H2O (3), [Cu(H2O)3(terpy)][CrCu(H2O)(terpy)(C2O4)3]2·9H2O (4), [Cu(H2O)(terpy)(NO3)][CrCu(H2O)(terpy) (C2O4)3]·6H2O (5), [CrCu2(terpy)2(C2O4)3(NO3)2]·1.5H2O·CH3OH (6) and [Cr2Cu4(H2O)4(terpy)4(C2O4)6] [Cr2Cu2(terpy)2(C2O4)6]·10H2O (7) were obtained from the reaction of an aqueous solution of the building block [Cr(C2O4)3]3− and a methanol solution containing Cu2+ ions and the terpyridine ligand by the layering technique. Interestingly, changing only the anion of the starting salt of copper(II), NO3− instead of Cl−, resulted in an unexpected change in the bridge type, oxalate (compounds 2−7) versus chloride (compound 1), which affected the overall structural architecture. Compounds were studied by single- crystal X-ray diffraction, IR spectroscopy, magnetization measurements and density functional theory (DFT) calculations.

The oxalate group, C2O42-, used in the preparation of metal-organic coordination compounds, has the ability to bind to metal ions in various modes, which allows the synthesis of various structures, of different dimensionality and nuclearity. Its ability to mediate magnetic interaction between the paramagnetic metal centers, depending on the nature of the bridged metal ions, makes it a good ligand that can form compounds with ferro-, antiferro- or ferrimagnetic ordering. These compounds can combine several properties of the interest ; intrinsic properties of the host with additional functionalities originating from the selected guest molecules can result in materials with multifunctional properties. Oxalate polymers are mostly negatively charged and therefore can associate with different molecular cations, and combine cooperative magnetism with another property of interest.1 The proton conductivity of metal-organic networks has been intensively researched because of their crystallinity, high porosity, designability and tunability in structure and properties. As a new functionality of metal-organic compounds it can be achieved by incorporating a counterion such as hydronium (H3O+), ammonium [NH4+, (CH3)2NH2+, ...] or an anion (SO42−) into the anionic network during synthesis. The counterions form the hydrogen bonds with the guest water or other components of compound and create proton-conducting pathways consisting of hydrogen bonding networks. The oxygen atoms of the oxalate group can construct complex hydrogen-bonded networks with water, which are more than suitable for proton conduction.2 We investigated the proton conductivity behaviour of the novel oxalate-based coordination compounds: (NH4)2[Fe(H2O)Cl3(C2O4)]·H2O (1), {; ; ; [NH(CH3)2(C2H5)][FeCl2(C2O4)]·H2O}; ; ; n (2), {; ; ; [NH(CH3)(C2H5)2]8[Mn4Cl4Cr4(C2O4)12]}; ; ; n (3) and {; ; ; [NH(CH3)2(C2H5)]8[Mn4Cl4Cr4(C2O4)12]}; ; ; n (4). The discrete mononuclear compound 1 exhibits remarkable humidity-sensing properties and a very high proton conductivity of 2.17 × 10−3 (Ω cm)−1 at 298 K under 74% relative humidity (RH). The one-dimensional (1D) compound 2 containing infinite anionic zig-zag chains [FeCl2(C2O4)]nn− and cations (CH3)2(C2H5)NH+ located between them, shows an increase in conductivity of six orders of magnitude with increasing RH, reaching values of 2.00 × 10−4 (Ω cm)−1 at 298 K and 93% RH. Compounds 3 and 4 consisting of two-dimensional (2D) oxalate-bridged anionic layers [Mn4Cl4Cr4(C2O4)12]n8n− interleaved by the hydrogen-bonded templating cations (CH3)(C2H5)2NH+ (3) or (CH3)2(C2H5)NH+ (4), exhibit extraordinary humidity-sensing properties and very high proton conductivity of 9.6 × 10−4 (Ω·cm)−1 at 298 K under 94% RH and 1.60 × 10−3 (Ω·cm)−1 at 298 K under 90% RH, respectively.

One of the most versatil ligands used in preparation of the magnetic materialst, the oxalate group, C2O42-, has shown various coordination modes towards the metal centres. Its ability to mediate magnetic interactions between paramagnetic metal ions as well as its ability to different nuclearity, conectivity and dimensionality of oxalate-based transition-metal species have been given us meny new complexes componds [1]. To make proton-conducting pathways composed of hydrogen-bond networks and to obtain conductive compound, proton carries is itroduced directly as counterions such as NH4+ or H3O+[2]. Therefore, various small molecule of alkyl ammonium cations are used for preparation of novel homo- and heteropolynuclear oxalate-based systems. By varying the amount of reactants tris(oxalato)chromate A3[CrIII(C2O4)3] [A = (C2H5)2(CH3)NH+ or (C2H5)(CH3)2NH+], as ligands towards second transition metal ion (MnII) the different compouns has been synthesied and characterised. For reatio 1:1:1 we have got dinuclear chain of A and for reatio 1:2:2 trinuclear compound Ba or Bb depend on amines. {;[NH(CH3)(C2H5)2][Cr(bpy)(μ-C2O4)2MnCl2]};n (1) (1 ; bpy = .2, 2'-bipyridine) and {;[NH(CH3)(C2H5)2] [Cr(C2O4)(μ-C2O4)2[Mn(bpy)(H2O)Cl]2}; (2a) {;[NH(CH3)2(C2H5)] [Cr(C2O4)(μ-C2O4)2[Mn(bpy) (H2O)Cl]2}; (2b).

Multifunctional properties of the coordination polymers can often be achieved by combining the intrinsic properties of the host, especially the magnetic ones, with an additional functionalities coming from the selected guest molecules [1]. The oxalate group, C2O42, has been demonstrated to be one of the most versatile ligands used in the preparation of these systems. Due to its various coordination modes towards the metal centres as well as its ability to mediate magnetic interactions between paramagnetic metal ions, a large number of oxalate-based transition-metal species of different nuclearity, connectivity and dimensionality have been synthesized and characterized, many of them having tunable magnetic frameworks [2]. Since their discovery, homo- and heterometallic 2D and 3D oxalate-based extended networks of a general formula [MaII/IIIMbI/II(C2O4)]n2n–/n–, obtained from a combination of tris(oxalate)metalates, [MIII(C2O4)3]3–, with other metallic ions, using different template cations, have attracted a lot of attention. The anionic networks provide magnetic properties (ferro-, antiferro-, or ferrimagnetic ordering) depending on the nature of the connected metal ions. Furthermore, these reported polymers are mostly negatively charged and therefore can be combined with different (functional) molecular cations in order to afford salts combining cooperative magnetism with a second property of interest hence forming multifunctional materials. Recently published oxalate-based networks have shown high humidity-dependent proton conductivity related to the presence of substituted ammonium and/or crystallization water which form hydrophilic layers that enabled conductive pathways of protons [2, 3]. To achieve our final goal – the development of materials containing noteworthy structural, magnetic and/or electrical features, novel homo- and heteropolynuclear oxalate-based systems have been synthesized using tris(oxalato)metalates, [MIII(C2O4)3]3– (MIII = Cr or Fe), as ligands towards second transition metal ion (MnII or CuII) and N, N-diethylmethylamine or N, N- dimethylethylamine. In addition to the single crystal X-ray diffraction study, characterization of the new complexes has been accomplished by means of the IR spectroscopy and thermal analysis.

In the field of molecular magnetism, the oxalate group, C2O4 2-, has been demonstrated to be one of the most versatile ligands used in the preparation of the magnetic materials. Due to its various coordination modes towards the metal centres as well as its ability to mediate magnetic interactions between paramagnetic metal ions, a large number of oxalate-based transitionmetal species of different nuclearity, connectivity and dimensionality have been synthesized and characterized, many of them having tunable magnetic frameworks[1] Furthermore, oxalate-bridged crystalline coordination polymers have been studied as hydrated proton-conductive systems owing to their high crystallinity and high stability for water. Generally, the existence of hydrated protons is required to achieve high proton conductivity of solids at ambient temperature. The studies of proton conduction in coordination polymers mainly include two kinds of situations: one is that under the anhydrous condition, it mainly relies on the inherent water molecules or other minor molecules containing protons and hydrogenbond network in the structures to carry out the proton transfer ; another one is that under the aqueous condition, the external H2O units play a vital function on the proton transmission.[2] To achieve our final goal – exploration of the complexes containing noteworthy structural, magnetic and electrical features, two novel homo- and heterometallic oxalate-based systems have been synthesized and characterized using tris(oxalato)chromate, A3[CrIII(C2O4)3] [A = (C2H5)2(CH3)NH+ or (C2H5)(CH3)2NH+ ], as ligands towards second transition metal ion (MnII or CuII): {; ; [NH(CH3)(C2H5)2][Cr(bpy)(μ- C2O4)2MnCl2]}; ; n (1 ; bpy = 2, 2'-bipyridine) and [NH(CH3)2(C2H5)][Cr(H2O)(C2O4)2] (2).

The design and synthesis of new materials with targeted physical properties represents an operative area of research for materials scientists. The combination of magnetic oxalate- based coordination polymers with organic/inorganic functional cations provides a suitable approach for designing hybrid magnetic materials exhibiting multifunctional properties. The oxalate moiety, C2O4 2−, acts as a linker between metal centers, with various possibilities of coordination to metal centers yielding open structures with dimensionalities ranging from 0 to 3. A property of oxalate ions that has been of specific interest is their ability to mediate electronic effects between paramagnetic metal ions. Proton conductivity is a new performance of the coordination polymers since they could provide required proton-conducting pathways, mostly by introducing (i) the guest molecules and counterions or acids into the voids, creating complicated hydrogen-bonded networks ; (ii) other functional groups which can improve the acidity and hydrophilicity of the organic ligands and thus form an efficient proton transport pathway. Three novel oxalate-bridged coordination polymers have been synthesized using [Cr(C2O4)3] 3− as building block: 1D homometallic {; ; ; ; [Mn(bpy) (C2O4)]·1.5H2O}; ; ; ; n (1) (bpy = 2, 2'-bipyridine) and heterodimetallic {; ; ; ; [CrCu3(bpy)3(CH3OH)(H2O) (C2O4)4] [Cu(bpy)Cr(C2O4)3]·CH2Cl2·CH3OH·H2O}; ; ; ; n (2), as well as 3D heterotrimetallic {; ; ; ; [CaCr2Cu2(phen)4(C2O4)6]·4CH3CN·2H2O}; ; ; ; n (3) (1, 10- phenanthroline), and their structural diversity is reflected on magnetic and electrical properties which have been studied. The Mn-chains of 1 are antiferromagnetic ; 2 shows the existence of antiferromagnetic oxalate-bridged Cu2+ dimers, which are independent from the oxalate- bridged Cu2+ and Cr3+ ions interacting ferromagnetically ; 3 displays dimeric behavior, with Cu2+ and Cr3+ ions coupled ferromagnetically. Further, polymers 1 and 3 exhibit lower electrical conductivity at RT in comparison to compound 2.

Multifunctional properties of the metal-organic coordination polymers can be achieved by combining the intrinsic properties of the host, especially the magnetic ones, with an additional functionalities coming from the selected guest molecules. The oxalate group, C2O42, has been demonstrated to be one of the most versatile ligands used in the preparation of these systems. Due to its various coordination modes towards the metal centres as well as its ability to mediate magnetic interactions between paramagnetic metal ions, a large number of oxalate-based transition- metal species of different nuclearity, connectivity and dimensionality have been synthesized and characterized, many of them having tunable magnetic frameworks. Furthermore, the simplest method to obtain conductive compound is to introduce proton carries directly as counterions such as NH4+, H3O+ and to make proton-conducting pathways composed of hydrogen- bond networks [1]. In previous work, we reported one-dimensional antiferromagnetic oxalate-bridged coordination polymer {; ; ; [NH(CH3)2(C2H5)] [FeCl2(C2O4)]}; ; ; n, showing hydrogen-bonded diethylmethylammonium cationic moieties what lead to a very high room- temperature proton conductivity [2.70×10−4 ( cm) −1 under 93% relative humidity conditions]. Therefore, we have continued to prepare oxalate systems containing various alkyl ammonium cationic components, with the aim of obtaining compounds which, in addition to interesting magnetic properties, also show proton conductivity. In order to obtained such heterometallic complexes, tris(oxalato)metalates, [MIII(C2O4)3]3– (MIII = Cr or Fe), are used as ligands towards second transition metal ion.

Due to the rich variety of metal species and ligands, coordination geometry, guests inside the pores, and supramolecular structures, an enormous number of coordination polymers with various structures, dimensionality, and nuclearity have been synthesized and reported. This area of molecular chemistry is the basis for design of the molecule-based materials that combine two (or more) physical properties of interest, especially upgrading and expanding the molecular magnetism toward multifunctional systems. Most of the oxalate-based molecular magnets described to date have been obtained by the “complex-as-ligand approach” ; a molecular building block, the tris(oxalato)metalate [MIII(C2O4)3]3 anion is used as a ligand toward other metal cations. The topology of these oxalate-bridged compounds is controlled by a templating counterion. Two polymorphs of 3D coordination polymer [CuIIFeII2(H2O)(terpy)(C2O4)3]n (1 ; terpy = 2, 2′:6′, 2′′-terpyridine), formed hydrothermally, contain homometallic 2D oxalate-bridged honeycomb anionic layers, [FeII2(C2O4)3]n2n-, mutually linked by complex cations of copper(II) ions, [Cu(H2O)(terpy)]2+, through oxygen atoms from oxalate bridges. Recently published oxalate-based networks have shown proton conductivity related to the presence of ammonium and/or crystallization water [1]. Therefore, in addition to magnetic, electrical properties of 1 have been also investigated ; it exhibits antiferromagnetic phase transition at 25 K and proton conductivity. Furthermore, the ability of this 3D polymer, due to their appropriate stoichiometry of metal ions, to act as single-source precursor for the formation of spinel CuFe2O4 oxide by heat treatment has been explored [2].

Coordination polymers with metal-organic frameworks and organic or inorganic functional cations offer many possibilities in constructing interesting multifunctional materials such as ferromagnetic conductors, photo and piezo switching magnets, chiral magnets and multiferroics. Especially interesting are oxalate-based compounds, where the C2O42-acts as a linker between metal centres and provides various possibilities of coordination to metal centres resulting in structures with different dimensionalities. The other useful property of oxalate ions is their ability to mediate super-exchange interaction.In this work we will present magnetic behaviour of three novel metal-organic coordination polymers synthetized by a layering technique. The investigated compounds consist of single or multi metal cations bridged by an oxalate ion. The first compound, {; ; Mn(bpy) (C2O4) ·1.5H2O }; ; n, has a 1D chain structure, where the chains are connected by πinteractions between 2, 2’ bipyridyl molecules coordinated on the manganese ions of neighbouring chains. The second compound, {; ; [CrCu(bpy)(C2O4)3] [CrCu3(bpy)3(CH3OH)(H2O) (C2O4)4]·CH2Cl2·CH3OH·H2O}; ; n , consists of two kinds of chains in which two metal ions, chromium and copper ions, are bridged by the oxalate ion. The 2, 2’-bipyridyl molecules are coordinated on the copper ions, enabling the existence of πinteraction between the chains. One chain consists of only Cu and Cr ions bridged by oxalate, while the other chain has two more Cu atoms connected to the Cr ion. The third compound, {; ; [CaCr2Cu2(phen) (C2O4)6]n·4CH3CN·2H2O}; ; n, is a two dimensional coordination polymer which consists of copper, chromium and calcium ions bridged by the oxalate bridge in the 2D network. The molecule coordinated on the copper is a 1, 10- phenanthroline. The magnetic properties of polycrystalline samples in powder form were investigated using a MPMS5 SQUID magnetometer. Temperature dependence of magnetization was measured in the temperature range 2 -400 K, measuring both zero field cooled (ZFC) and field cooled (FC) magnetization curves. The MT curve of a single metal chain compound showed a broad peak at 15K, characteristic of antiferromagnetic chains, while the other two compounds show curves similar to the paramagnetic ones, with no maximum, or saturation at low temperatures, indicating a more complex magnetic coupling. The field dependence of magnetization was measured up to 5 T. The MH curve for the first compound is almost linear with no saturation, characteristic of antiferromagnetic chains, and the value of 1.1 μB/f.u. at 5T and 2K. The second and third compound show saturation of the magnetization at the value of 8 and 7 μB/f.u. respectively, indicating ferromagnetic or ferrimagnetic coupling of Cu and Cr ions.

U proizvodnom pogonu "tokarsko bravarski obrt“ obradili smo za ovaj rad ispitivanje buke i rasvjete u radnom okolišu. Tvrtka u kojoj smo radili ispitivanje bavi se izradom bravarije, koje su vezane za brodogradnnju i strojarstvom, te uz to obradom i reparacijom motora. U radu smo prikazali ispitivanje radnih prostorija prema zakonskim parametrima, koji propisuje zakon o zaštiti na radu (NN br. 71/14, 118,/14 i 154/14) i pravilniku o zaštiti radnika od same izloženosti buci (NN. Br. 46/08). Opisali smo poslove koje radnici obavljaju i s kojim se srestvima alatima koriste pri izvođenju, utvrdili koje opasnosti bi mogle naštetiti radniku i kojim sve naporima se susreće radnik pri izvođenju zadataka, prikazali mjere zaštite na radu pri njihovom izvođenju kroz primjenjivanje osnovnih i posebnih pravila i predložili sigurnosne mjere za zaštitu i poboljšanje rada radnika pri izvođenju poslova, ako već ne postoje. In the production plant "Turning Locksmith's Craft" we have processed for this work the testing of noise and lighting in the working environment. we have presented the examination of working premises according to the legal parameters, which are prescribed by the Occupational Safety and Health Act (OG No. 71/14, 118, / 14 and 154/14) and the Ordinance on the protection of workers from exposure to noise (OG No. 46/08 ) proposed safety measures to protect and improve the work of workers in the performance of their duties, if they do not already exist.

Kava je jedan od omiljenih napitaka uz čaj i kakao te predstavlja jedan od izvora klorogenskih kiselina u svakodnevnoj prehrani. Klorogenske kiseline ubrajaju se u grupu hidroksicimetnih kiselina poznatih po svom zaštitnom utjecaju na zdravlje ljudi. Zadatak ovog diplomskog rada bio je primjena diferencijalne pulsne voltametrije na elektrokemijsko ponašanje klorogenskih kiselina u instant kavama (Jacobs Monarch, Nescaffé Gold, Jacobs Cronat Gold i Franck Classical). Ispitivanje elektrokemijskog ponašanja provedeno je u troelektrodnoj ćeliji s radnom elektrodom od staklastog ugljika, referentna elektroda srebro/srebro klorid i protuelektrodom žicom platine. Elektrokemijska mjerenja odvijala su se u fosfatnom puferu različitih pH vrijednosti. Na osnovi istraživanja elektrokemijskih svojstava klorogenske kiseline u usporedbi s kafeonskom kiselinom, a primjenom DPV metode, može se zaključiti da na njihova elektrokemijska svojstva značajno utječe kemijska struktura, primijenjena višestruka uzastopna polarizacija i koncentracije analita. Rezultati sadržaja ukupnih klorogenskih kiselina u ispitivanim kavama dobiveni primjenom elektrokemijske metode uspoređeni su s rezultatima ukupnih polifenola dobivenih primjenom spektrofotometrijske Folin-Ciocalteu metode. Prema sadržaju klorogenskih kiselina može se zaključiti da su ispitane vrste kave sličnog sadržaja klorogenskih kiselina. Coffee is one of the favourite drinks together with tea and cocoa and is one of the chlorogenic acids sources in daily diet. Chlorogenic acids are part of the group of hydroxycinnamic acids known after their protective effect on human health. The aim of this work was the application of differential pulse voltammetry to the electrochemical behaviour of chlorogenic acids in instant coffee (Jacobs Monarch, Nescaffé Gold, Jacobs Cronat Gold and Franck Classical). Electrochemical behaviour was carried out in a three-electrode cell with a glassy carbon working electrode, reference electrode silver/silver chloride and platinum wire counter electrode. Electrochemical measurements were carried out in phosphate buffer of different pH values. Based on the investigation of the electrochemical properties of chlorogenic acids compared to caffeic acid, and with the application of DPV methods, it can be concluded that their electrochemical properties are significantly influenced by the chemical structure, the applied multiple polarization and the concentration of the analyte. The results of total chlorogenic acids content in the investigated coffee obtained using the electrochemical method were compared with the results of the total polyphenols obtained using the spectrophotometric Folin-Ciocalteu method. According to the chlorogenic acids content, it can be concluded that the investigated coffee have a similar content of chlorogenic acids.

The perovskite family of oxides is very attractive area of research in material science community because of the diversity of their physical and chemical characteristics, which offers opportunity to explore new functionalities and potential applications, such as photocatalysis, light harvesting, superconductivity, magnetoresistance, ferroelectric, multiferroic or dielectric performance. In general complex perovskite oxides with A2B'B''O6 or A3B'B''B'''O9 formula, where A are alkali, alkaline earth or rare earth elements, while the B', B'' and B''' cations can be any transition element, have crystal structure that consists of the corner sharing B'O6, B''O6 and B'''O6 octahedra, and A atoms located in the space between the octahedra. A variety of devices and methods have previously been used to prepare and characterize perovskite compounds, however most common method of their preparation is solid state reaction at high temperatures. Herein we propose novel pathway for the synthesis of perovskite-type oxides through molecular precursor-to-material approach, which uses heterometallic complexes as precursors for oxides. Thermal decomposition of the mixture of the well-defined and structurally characterized heterometallic oxalate-based compounds {; ; ; Ba2(H2O)5[NbO(C2O4)3]HC2O4}; ; ; ·H2O and [Ni(bpy)3]2[TaO(C2O4)3]Cl·12H2O leads to highly crystalline Ba3(NiNbTa)O9 oxide. We have also shown that Ba2NbCrO6 perovskite-type oxide can be obtained in thermal treatment of {; ; ; Ba2(H2O)5[NbO(C2O4)3]HC2O4}; ; ; ·H2O and (NH4)3[Cr(C2O4)3]·3H2O. The phase formation and structural ordering of oxides obtained by modified molecular precursor- to-material method has been investigated through a combination of thermal analysis (TGA and DTA), powder X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. We have shown that ratio of metals can be finely tuned with the careful choice of molecular precursors as well as by appropriate amount of initial heterometallic complexes taken for the thermal decomposition reaction. The preparation strategy described here could be extended for the synthesis of various other complex perovskites at relatively mild conditions.